Immunostimulatory RNA is a potent inducer of antigen-specific cytotoxic and humoral immune response in vivo

Int Immunol. 2007 Mar;19(3):297-304. doi: 10.1093/intimm/dxl146. Epub 2007 Feb 7.


Single-stranded RNA stimulates immune cells and induces the secretion of pro-inflammatory cytokines and type I IFN. As adjuvant RNA can induce a T(h)2 type of humoral response, however, its potency in the induction of cytotoxic T cells in vivo has not been analyzed. Here we show that immunization with the antigen ovalbumin (OVA) and the adjuvant phosphodiester RNA complexed to the cationic lipid N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium methylsulfate (DOTAP) induced a Toll-like receptor-7-dependent cytotoxic T cell and humoral response. Staining with SIINFEKL-K(b) tetramers demonstrated the induction of antigen-specific T cells that were functional in in vivo cytotoxic T cell assays against SIINFEKL-loaded target cells. In infection experiments with OVA-secreting Listeria monocytogenes, the cytotoxic T cell response strongly reduced the bacterial load in liver and spleen. The RNA-driven humoral response was characterized by OVA-specific antibodies of the IgG1 isotype whereas CpG-DNA induced antigen-specific antibodies of the IgG2a (BALB/c) or IgG2c (C57BL/6) isotype. Furthermore, stimulation with RNA did not induce splenomegaly, a common feature of CpG-DNA-driven immune activation in mice. Taken together, our data confirm that RNA can be used as a safe adjuvant and induces a strong antibody response of the IgG1 isotype. Additionally, we demonstrate that RNA induces an antigen-specific immunity characterized by a potent cytotoxic T cell response to infection.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adjuvants, Immunologic* / toxicity
  • Animals
  • Antibody Formation
  • Antigens / immunology
  • Bacterial Vaccines / immunology*
  • Bacterial Vaccines / toxicity
  • Cells, Cultured
  • Disease Models, Animal
  • Fatty Acids, Monounsaturated / immunology
  • Female
  • Immunization
  • Immunoglobulin G / blood
  • Listeria monocytogenes / immunology*
  • Listeriosis / immunology
  • Listeriosis / prevention & control
  • Lymphocyte Activation
  • Membrane Glycoproteins / deficiency
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / immunology*
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Oligodeoxyribonucleotides / immunology
  • Oligonucleotides / immunology*
  • Oligonucleotides / toxicity
  • Ovalbumin / immunology
  • Quaternary Ammonium Compounds / immunology
  • RNA / immunology*
  • RNA / toxicity
  • T-Lymphocytes, Cytotoxic / immunology*
  • Th2 Cells / immunology
  • Toll-Like Receptor 7 / deficiency
  • Toll-Like Receptor 7 / genetics
  • Toll-Like Receptor 7 / immunology*


  • Adjuvants, Immunologic
  • Antigens
  • Bacterial Vaccines
  • CPG-oligonucleotide
  • Fatty Acids, Monounsaturated
  • Immunoglobulin G
  • Membrane Glycoproteins
  • Oligodeoxyribonucleotides
  • Oligonucleotides
  • Quaternary Ammonium Compounds
  • Tlr7 protein, mouse
  • Toll-Like Receptor 7
  • RNA
  • Ovalbumin
  • 1,2-dioleoyloxy-3-(trimethylammonium)propane